The aim of this paper is to evaluate the effect of planeload of a heavy off-the-road dump truck on the compaction of a thick finishing decomposed granite soil. The compaction test using off-the-road tire was executed in a large soil bin. A proposed soil compaction model was used to predict dry density of sandy soil. It was estimated that the pressure bulb reached the depth of a thick layer under tandem wheels. Furthermore, it also shows that the dry density achieved a comparatively high value due to the dilatancy effect accompanying with an occurrence of alternative shear stress during the running of dump truck, and the dry density decreased rapidly to the low constant value at the deep stratum.